1. Field of the Invention
The present invention relates to surgical devices and methods, and, more particularly, to orthopedic devices and methods for fixating soft tissue and reducing fractures.
2. Description of Related Art
Orthopedic procedures are typically undertaken to repair structural injuries or address structural problems. Among these are fracture reduction and the fixation of soft tissue tears.
Soft tissue tears are often desired to be treated by placing the two sides of the tear into intimate (or tight) apposition to permit healing. This can be achieved, for example, by suturing the tear or by placing an implement into the tissue to breach the tear and bring the sides together.
A common soft tissue tear, especially in athletes, occurs in the menisci of the knee. Posterior peripheral tears of the menisci may be treated by an open technique, wherein sutures are placed along the tear. An arthroscopic technique may also comprise placing sutures along the tear or inserting a meniscal dart or screw of one of the types known in the art. Screws having heads, however, are known to cause problems within a joint, even if they are resorbable, since a typical resorption time is in the range of 6-9 months. Further, screws and darts are typically substantially rigid elements that can cause discomfort in the patient.
There are a number of fastener-type devices known in the art. A surgical fastener is disclosed by Screiber (U.S. Pat. No. 4,873,976) that comprises a shaft having at least one barb for locking the shaft in place when inserted into soft tissue. Bays et al. (U.S. Pat. Nos. 4,884,572 and 4,895,148) describe a surgical-repair tack and applicator and method of using them. The tack has a barb member and is made of biodegradable material having a degradation time selected to coincide with the healing time of the tissue. In an alternate embodiment, the tack""s barb comprises a continuous helical barb.
A method and apparatus for repairing a meniscal tear is disclosed by Winters (U.S. Pat. No. 5,059,206), comprising a fastener having protrusions or barbs that is applied to a meniscal tear with a delivery device. Variable-pitch bioresorbable meniscal screws that are insertable across a tear are also taught by Justin and Winters (U.S. Pat. Nos. 5,569,252 and 5,730,744).
Another example of an orthopedic injury the treatment of which could be improved is a torn carpal ligament, which will permit the carpal bones to spread apart without securing them together during the healing process. At present this is addressed by connecting the affected bones with smooth pins, necessitating the immobilization of the wrist. These pins must then be removed after healing.
Yet another example of a fracture is the crushing of the distal aspect of the radial bone, which can leave a posterior defect after the reduction adjacent the bone""s head. Such a fracture cannot be treated simply by applying a cast, since, left unattended, the wedgelike defect will permit the radius to deform upward to close the gap.
Current methods of treating such fractures include affixing plates to the bone, a procedure that is painful and may injure adjacent tendons; injecting paste into the defect zone, which does not consistently effect a correction and which cannot be modified once the paste sets; and inserting pins or external fixation, which can cause stress risers in the adjacent bone that can lead to stress fractures or loss of reduction from not directly supporting the bone defect.
It is therefore an object of the present invention to provide a device and method for reducing fractures.
It is a further object to provide such a device that biases the two sides of a wedge-shaped bone defect into a natural position to promote proper healing.
It is another object to provide such a device that does not impinge upon surrounding soft tissue.
It is an additional object to provide such a device that is insertable arthroscopically or percutaneously.
It is yet a further object to provide a device and method for fixating a soft tissue tear.
It is yet another object to provide such a device that brings two sides of a soft tissue tear into apposition to promote healing.
An additional object is to provide a device and method for compressing adjacent bones during the healing of a connecting ligament without excessive constraint and maintaining a desired physiological relationship.
A further object is to provide a device and method for promoting healing of a fixated soft tissue tear.
Another object is to provide a device and method for creating a vascular access channel.
These and other objects are achieved by the present invention, an orthopedic reduction and fixation device, insertion system, and associated methods. The system for fixation of a soft tissue tear comprises the device, which in one embodiment comprises a flexible, generally helical fixation element biased to a predetermined pitch. In an alternate embodiment the device comprises a helical portion and a nonhelical portion, the helical portion biased to a predetermined pitch. In yet another embodiment the helix is biased to a first pitch along a distal portion, a second pitch along a central portion, and a third pitch along a proximal portion. The second pitch is smaller than the first and the third pitches, so that, upon insertion across a tear, the central portion will contract, bringing the sides of the tear closer together to promote healing.
The system also includes a hollow, generally helical insertion element dimensioned to admit at least a distal portion of the fixation element into a lumen thereof. The insertion element in one embodiment has a first pitch along a distal portion, a second pitch along a central portion, and a third pitch along a proximal portion. The second pitch is larger than the first and the third pitches and is also larger than the fixation element predetermined pitch. The insertion element is further insertable in a screwing motion across the soft tissue tear and is positionable with the central portion bridging the tear.
The fixation element is insertable into the insertion element, and the insertion element is removable in a reverse screwing motion, leaving the fixation element positioned across the tear. The positioning of the central portion permits the fixation element to contract following removal of the insertion element to bring the two bridged sides of the tear together, permitting them to heal.
Among the many advantages of the helical fixation element is its dynamic nature; unlike a rigid or semirigid screw, a flexible helix can move with the tissue, accommodating stresses laterally and under compression and stretching, while returning to its natural predetermined pitch. Alternatively, in some embodiments the element may have a higher level of stiffness, particularly along the portion of the element bridging the tear, to resist stretching/elongation under physiological conditions. Additionally, since the device is headless, there can be no additional trauma caused by such a protrusion. Further, since a helical structure can be inserted into a hole only as large as the diameter of the coil element, the wound needed for insertion is far smaller than would be required for another type of anchoring element, such as a screw; the resistance to pullout is also much better, an axial force alone not being able to achieve removal. It is also believed that the helical device can effect greater compression than a screw. In addition, even if the coil breaks in the tissue, the complex fixation with the tissue enables a maintenance of structural integrity.
A further embodiment of the invention comprises suture material as a component of the fixation element. In a first subembodiment suture material resides within an insertion element lumen for insertion. Upon withdrawal of the insertion element the suture material remains, along a substantially helical pathway, essentially xe2x80x9cstitchingxe2x80x9d the tear together. In a second subembodiment the fixation element comprises a nonresorbable suture material core surrounded by a resorbable, shape-retaining material formed into a substantially helical shape along at least a portion thereof adapted for placement across the tear. In use, then, when the fixation element is placed across the tear, the resorbable material preferably remains in place for a time commensurate with a healing time; following resorption, the suture material remains, providing permanently added stability.
Another embodiment of the invention comprises an orthopedic system for stabilizing two sections of a bone in spaced-apart relation, such as is desired in crushing-type injury to a wrist. The system includes an insertion guide that comprises an elongated guide element having a length sufficient to span a bone requiring fixation. The guide element also has a diameter that is dimensioned for insertion through a bore in the bone or through a fracture defect. The insertion guide also comprises means for preventing a distal end of the guide element from entering the bone bore. The preventing means may comprise a deployable element that is movable between an insertion orientation and an anchoring orientation wherein the guide element from entering the bone bore.
The system further includes a coil element that is dimensioned for insertion into a fracture or defect and has a bore dimensioned for threading over the guide element. The coil element is biased in an outward direction for fixating two sections of bone in a desired spaced-apart orientation.